I think everyone would want to be doing what they love doing when it came time for them to die. I think this was his time.
Where ever the mind goes the body will follow...follow your dreams. He followed his, running in the wilderness. This time on a short run, but without his best friend and companion. I believe he is at peace knowing he lived his life to the fullest. His best friend lost his best friend, but does not know he will not be coming back.